Impeller and method of manufacturing same

ABSTRACT

A method of manufacturing a pump impeller and a pump impeller which is constructed primarily in a single molding operation. The pump impeller has a shroud which includes an inlet opening located on one side of a series of vanes. On the opposite side of the series of vanes is a hub and from the hub extends a shaft sleeve. The axis of rotation of the shaft sleeve aligns with the longitudinal center axis of the inlet opening.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to impellers for centrifugal pumps andmore specifically to a pump impeller that is constructed to be inprecise alignment and the method of manufacturing same.

[0003] 2. Description of the Related Art

[0004] A well known impeller for centrifugal pumps uses a series ofradially extending vanes. Rotation of the impeller causes liquid whichis being supplied to the center area of the impeller to be radiallyaccelerated and dispensed from the periphery of the impeller. A typicalpump impeller is essentially composed of three parts. These parts arehub, vanes and shroud. In the past, the typical way to manufacture suchan impeller is to mold the vanes, mold the shroud, mold the hub and thenphysically connect the parts together by some means, such as welding oradhesive. A strong attempt is made to align the longitudinal axis of theshroud with the axis of rotation of the motor drive shaft. However,normal misalignment up to 0.060 inches is common. An additionalmanufacturing step is required of machining the annular inlet ring whichis integral to the shroud to correct this misalignment. The shroudfrequently turns slightly during the adhesion to the vanes whichproduces the misalignment.

[0005] The motor drive shaft, which is used to rotate the impeller, isconnected to the hub. Therefore, the hub rotates about the axis ofrotation. The shroud has an inlet opening through which liquid is to besupplied within the impeller. Surrounding the inlet opening is theannular inlet ring. If the longitudinal center axis of the annular inletring is not precisely aligned with the axis of rotation of the hub,there will inherently be caused a wobble. The wobble produces anundesirable vibration and noise. The wobble also accentuates prematurefailure and wear during operation of the pump. The wobble also causesinefficient operation of the pump. These disadvantages have been foundto be most undesirable especially in using of a pump in conjunction withswimming pools or spas.

[0006] It would be most desirable to design a pump impeller where theaxis of rotation of the hub is always precisely aligned with thelongitudinal center axis of the inlet opening thereby eliminatingundesirable vibration, noise and increasing pump efficiency.

SUMMARY OF THE INVENTION

[0007] The first basic embodiment of the present invention relates to amethod of manufacturing a pump impeller by forming in a single moldingoperation the shroud, vanes and shaft sleeve to obtain alignment of theaxis of rotation of the sleeve with the longitudinal center axis of anannular inlet ring mounted on the shroud.

[0008] A second basic embodiment of the present invention relates to apump impeller which utilizes a series of vanes to which is integrallyattached a shroud with the shroud having a centrally located annularinlet ring through which is an inlet opening which provides access tothe eye of the impeller. A hub is integrally connected to the inner endof the vanes with the hub having a sleeve integrally connected thereto.The sleeve has an axis of rotation and the inlet opening has alongitudinal center axis. Both of these axes are in alignment.

[0009] A further embodiment of the present invention is where a cover isto be mounted about the hub in direct contact and attached to the vanes.

[0010] A further embodiment of the present invention is where there is asleeve mounted on the hub.

[0011] A still further embodiment of the present invention is where thesleeve is at least one inch in length.

[0012] A further embodiment of the present invention is where the secondbasic embodiment has defined the inlet opening of the annular inlet ringto be of a size larger than the hub which facilitates its manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a better understanding of the present invention, reference isto be made to the accompanying drawings. It is to be understood that thepresent invention is not limited to the precise arrangement shown in thedrawings.

[0014]FIG. 1 is a side elevational view of the pump impeller of thepresent invention;

[0015]FIG. 2 is an end view of the pump impeller of the presentinvention taken along line 2-2 of FIG. 1;

[0016]FIG. 3 is a cross-sectional view through the pump impeller of thepresent invention taken along line 3-3 of FIG. 1; and

[0017]FIG. 4 is a longitudinal view, partly in cross-section, throughthe pump impeller of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] Referring particularly to the drawings, there is shown a pump 10which has a pump housing 12. The pump housing 12 is designed to beconnected to a motor housing 13. The motor housing 13 is to include anelectrically operated motor which when operated will cause rotation of amotor shaft 14. The free outer end of the motor shaft 14 includes aseries of threads 16. The motor shaft 14 includes an axis of rotation18.

[0019] The housing 12 has an internal chamber 20 and inlet conduit 30. Adischarge conduit 28 has an internal passage 31 which connects tointernal chamber 20. Pump impeller 34 is rotatably mounted withininternal chamber 20. The internal chamber 20 also connects with inletconduit 30 which has an internal passage 29. Surrounding the inletconduit 30 and formed within the internal chamber 20 is an annulargroove 32.

[0020] The pump impeller 34 has a shroud 36 which is basicallydisc-shaped. The shroud 36 includes an annular inlet ring 38. Theannular inlet ring 38 is centrally formed within the shroud 36 so thatin essence the shroud 36 is the shape of a ring. The annular inlet ring38 is rotatably mounted within the annular groove 32. Annular inlet ring38 has an inlet opening 40. Mounted on the inside surface of the shroud36 are a plurality of vanes 42. Each vane 42 is defined as being arcuateand extend from a hub 44 to the peripheral edge 35 of shroud 36. Thearrangement of the vanes 42 is deemed to be a matter of choice with atypical arrangement being where the vanes 42 are basically all of thesame length and of the same curvature, as shown in the drawings.However, the length of the vanes 42 and their pattern of arrangement andconfiguration could be altered without departing from the scope of thisinvention. There is shown eight in number of the vanes 42. Also, thenumber of the vanes 42 could be increased or decreased without departingfrom the scope of this invention.

[0021] It is to be noted that the diameter of the hub 44 is smaller thanthe diameter of the inlet opening 40. This is required so that theentire pump impeller 34 of this invention can be manufactured in onesingle unit except for the cover 46. Cover 46 comprises a disc and isdesigned to be placed about the hub 44 and to be welded or otherwisesecured to the vanes 42. Thus, in essence, the use of the cover 46 andthe shroud 36 form an enclosing chamber 37 that will permit the liquidonly to escape from the peripheral edge 35 of the pump impeller 34.Liquid is to be conducted through passage 29 of the inlet conduit 30 andto be deposited within the eye 48 of the pump impeller 34. Located inconjunction within the confines of the eye 48 is a mound 50 that is tofunction to assist in changing the flow of the liquid from an axialdirection to a radial direction and direct the flow outwardly to theperipheral edge 35 of the pump impeller 34.

[0022] The motor shaft 14 is fixedly attached to the pump impeller 34 bymeans of threads 16 which engage with an appropriate series of threadsmounted within the interior of a shaft sleeve 52 which is integral withmound 50. The axis of rotation 18 is to be in precise alignment with thelongitudinal center axis 54 of the annular inlet ring 38 and the inletopening 40. The shaft sleeve 52 will preferably be about one inch inlength with the inside diameter precisely fitting the shaft 14, forprecise alignment. For strength purposes in the attachment of the shaftsleeve 52 to the hub 44, there is formed a hub collar 56.

[0023] Pump impeller 34, is rotated by rotating of shaft 14 within shaftreceiving opening 15 found in motor housing 13. Rotating pump impeller34 causes liquid to be drwn from passage 29 into enclosing chamber 37,propelled radially outwardly past peripheral edge 35 through vaneopenings 33 (eight in number) into discharge passage 31 of dischargeconduit 28. Because the pump impeller 34 is not formed of several partsbut is formed of one part from the shaft sleeve 52 to the annular inletring 38 of the shroud 36, the axis of rotation 18 will be preciselyaligned (within 0.006 inches) with the longitudinal center axis 54preventing any kind of a wobble which is common when constructing of thepump impeller 34 of a multitude of parts which are welded togetherinherently creating a misalignment between the axes 18 and 54. Themaximum misalignment of 0.006 inches is totally acceptable.

What is claimed is:
 1. A method of manufacturing a pump impellercomprising: forming in a single molding operation a shroud, vanes andshaft sleeve so as to precisely obtain alignment of an axis of rotationof said sleeve with a longitudinal center axis of an annular inlet ringmounted on said shroud where said annular inlet ring and said sleeve areon opposite sides of said shroud, whereby during rotation of saidimpeller smooth, efficient substantially noise-free operation isobtained because said sleeve is in balance with said annular inlet ring.2. A pump impeller comprising: a series of vanes having an outer endwhich is integrally mounted on a shroud, said shroud having a centrallylocated annular inlet ring which provides an inlet to an eye of saidimpeller; and a hub integrally connected to an inner end of said vanes,said hub having a sleeve connected thereto, said sleeve having an axisof rotation, said inlet having a longitudinal center axis, said axis ofrotation being aligned with said longitudinal center axis, wherebyrotation of said impeller produces essentially no vibration with saidimpeller rotating smoothly, efficiently and substantially noise-free. 3.The pump impeller as defined in claim 2 wherein: a cover mounted on saidhub covering said vanes, said cover being located opposite said shroudrelative to said vanes substantially enclosing said vanes.
 4. The pumpimpeller as defined in claim 2 wherein: said sleeve located on one sideof said vanes and said shroud being located on the opposite side of saidvanes.
 5. The pump impeller as defined in claim 4 wherein: said sleevebeing at least one inch in length.
 6. The pump impeller as defined inclaim 2 wherein: said inlet being larger in size than said hub, wherebysaid inlet being larger than said hub, said pump impeller can bemanufactured in a single molding operation.